This invention relates to an improved sheet inverting system, and more particularly, to a low cost inverter adapted to be placed within the normal paper path of low volume copier/printer products while providing enhanced product design possibilities due to its compact configuration.
Although, a sheet inverter is referred to in the copier/printer art as an "inverter", its function is not necessarily to immediately turn the sheet over (i.e., exchange one face for the other). Its function is to effectively reverse the sheet orientation in its direction of motion. That is, to reverse the lead and trail edge orientation of the sheet. Typically, in inverters as disclosed here, the sheet is driven or fed by feed rollers or other suitable sheet driving mechanisms into a sheet reversing chute. By then reversing the motion of the sheet within the chute and feeding it back out from the chute, the desired reversal of the leading and trailing edges of the sheet in the sheet path is accomplished. Depending on the location and orientation of the inverter in a particular sheet path, this may, or may not, also accomplish the inversion (turning over) of the sheet. In some applications, for example, where the "inverter" is located at the corner of a 90.degree. to 180.degree. inherent bend in the copy sheet path, the inverter may be used to actually prevent inverting of a sheet at that point, i.e., to maintain the same side of the sheet face-up before and after this bend in the sheet path. On the other hand, if the entering and departing path of the sheet, to and from the inverter, is in substantially the same plane, the sheet will be inverted by the inverter. Thus, inverters have numerous applications in the handling of either original documents or copy sheets to either maintain, or change, the sheet orientation.
In the field of reprographic machines, it is often necessary to feed along one of two alternate paths a copy sheet leaving the processor of the machine, particularly when the machine can selectively produce simplex (one-sided) and duplex (two-sided) sheets. Simplex sheets may be fed directly to an output tray, whereas the duplex sheets may pass to a sheet feeder which automatically reverses the direction of movement of a simplex sheet and feed it back into the processor, but inverted, so that the appropriate data can be applied to the second side of the sheet. One known sheet-feeder (U.S. Pat. No. 4,359,217) for effecting this includes three rollers in frictional or geared contact with each other, to provide two spaced-apart nips, one being an input nip to an associated downstream sheet pocket, and the other being an output nip for extracting each sheet from the pocket. Another known sheet feeder (U.S. Pat. No. 4,735,409) includes four rollers and three spaced apart nips with one input up and two output nips. A sheet reversing apparatus for reorienting sheets so that a first side and an opposing side of the sheets may be operated upon is provided in U.S. Pat. No. 3,862,802 which includes a web for storing the sheets. These inverters have shortcomings when adaptation is attempted for insertion into low volume machines since they are costly, cumbersome and require more machine volume to implement than is desired. One of the reasons why the smallest, personal size copiers/printers do not print on both sides of a sheet is that the conventional inverting schemes would prohibitively enlarge the machine size. What has been mostly used are either flat trays or curved slots ("scorpion tail inverter") which require by their very nature certain minimum space.
The present invention aims at providing an inverter designed to have a sheet to be duplexed fed to it, stored momentarily, and wound to a much smaller diameter to save space. A roller pair is used to assist rolling and unrolling the sheet in order to prevent jamming one can expect at smaller radii of curvature.